The Impact of Femtosecond Laser on Intraocular Pressure with Cataract Surgery in Healthy Eyes.

PRCIS: Femtosecond laser-assisted cataract surgery leads to an increase in intraocular pressure (IOP) during the procedure and subsequent IOP reduction after surgery, with greater magnitude in eyes with higher preoperative IOP. PURPOSE: To evaluate the effect of femtosecond laser-assisted cataract surgery (FLACS) using the LDVZ8 laser on intraocular pressure (IOP) during and after surgery, and to compare the IOP-lowering effect of FLACS and conventional phacoemulsification cataract surgery (CPCS). PATIENTS AND METHODS: This prospective cohort study enrolled 395 healthy eyes (395 patients) scheduled for FLACS (n=245) and CPCS (n=150). FLACS was performed using the LDVZ8 laser. During FLACS, IOP was assessed before and immediately after docking. IOP reduction during a six-month postoperative period was evaluated following FLACS and CPCS. Multivariate analyses were performed. RESULTS: Mean IOP increase after docking was 2.3±4.1 mmHg (P<0.0001); maximum increase 17.6 mmHg, peak 38 mmHg. Sixty-one (61) eyes (25.1%) demonstrated an increase of ≥5 mmHg and 10 (3.7%) showed an increase of ≥10 mmHg; pre-docking IOP was associated with an IOP increase of ≥5 mmHg (P-0.029). IOP reduction over six months post-surgery was similar for FLACS and CPCS (P>0.05),-1.33±3.12 mmHg for FLACS (P<0.001) and -1.4±2.87 mmHg for CPCS (P<0.001). Preoperative IOP correlated statistically significantly with IOP reduction in both FLACS (ß -0.742, P<0.001) and CPCS (ß -0.743, P<0.001). CONCLUSIONS: Although the LDVZ8 laser procedure causes an increase in IOP in some healthy eyes, a subsequent decrease in IOP is observed after FLACS. The IOP-lowering effect of FLACS is similar to CPCS, and tends to be more pronounced in eyes with higher preoperative IOP. Eyes with higher preoperative IOP are prone to IOP elevation during FLACS, a critical consideration for glaucoma patients.

Factors associated with keratoconus in Israel-A cross-sectional population-based study.

PURPOSE: To identify potential factors associated with keratoconus. METHODS: This cross-sectional study included data from Israel's largest healthcare provider for the years 2005-2020. Keratoconus patients and age-matched controls were identified. Demographic factors and comorbid conditions, including smoking, diabetes mellitus, asthma, myalgia, mental retardation, Down syndrome, atopic dermatitis and allergy/allergic rhinitis, were compared between the two cohorts. The independent risk factors associated with keratoconus were determined using a multivariable conditional logistic regression model. RESULTS: Overall, 145 508 subjects were reviewed of which 13 228 were keratoconus patients. A ten-fold group (n = 132 280) of age-matched control subjects served as controls for comparisons. In multivariable analysis, several factors were found to be significantly associated with keratoconus. Male gender (OR = 1.27, p < 0.001), Arab ethnicity (OR = 1.50, p < 0.001), diabetes (OR = 1.19, p < 0.001), asthma (OR = 1.50, p < 0.001), myalgia (OR = 1.09, p = 0.02), mental retardation (OR = 2.63, p < 0.001), atopic dermatitis (OR = 1.35, p < 0.001) and allergic rhinitis (OR = 1.21, p < 0.001) were significantly associated with keratoconus. Smoking was significantly protective of keratoconus (OR = 0.66, p < 0.001). CONCLUSIONS: This population-based study reports male gender, Arab ethnicity, diabetes, asthma, myalgia, mental retardation/Down syndrome, atopic dermatitis and allergic rhinitis as factors associated with keratoconus while smoking demonstrates a protective effect. The results of this study could guide enhanced screening strategies and early interventions, particularly for high-risk groups.

Factors Predicting Loss of Best-Corrected Visual Acuity After Hyperopic Laser-Assisted In Situ Keratomileusis.

PURPOSE: The aim of this study was to identify risk factors for the loss of corrected distance visual acuity (CDVA) after uncomplicated hyperopic laser-assisted in situ keratomileusis (LASIK). METHODS: A retrospective study including hyperopic patients who underwent microkeratome-assisted LASIK between January 2000 and December 2019 at Care-Vision Laser Centers, Tel-Aviv, Israel. Loss of CDVA was defined as ≥ 2 lines (0.20 logarithm of the minimum angle of resolution [logMAR] increase). Excluded were patients who had loss of CDVA because of intraoperative or postoperative complications or developed cataract at their final visit. RESULTS: Overall, 1998 eyes of 1998 patients were included in the study, of which 35 eyes (1.75%) had CDVA loss at final follow-up (mean 387 days). The vision-loss group had a significantly greater spherical treatment (3.4 vs. 2.8 D, P = 0.02), ablation depth (69.4 vs. 53.8 µm, P = 0.01), a higher proportion of treatments with a smaller optic zone (6.0 mm) (31.4% vs. 13.4%, P = 0.002), treatment with the EX200 (Alcon) excimer rather than the EX500 (Alcon) (74.3% vs. 39.0%, P < 0.001), and treatment with the Moria M2-90 microkeratome rather than the Moria Sub-Bowman's keratomileusis (SBK) microkeratome (65.7% vs. 29.6%, P < 0.001). In multivariate binary logistic regression, factors that remained significant predictors of CDVA loss were a greater spherical treatment (per 1 D treatment, odds ratio = 1.42, 95% CI, 1.11-1.81, P = 0.004) and the use of the Moria M2-90 microkeratome (odds ratio = 4.66, 95% CI, 2.30-9.45, P < 0.001). CONCLUSIONS: In patients undergoing uncomplicated hyperopic LASIK, a greater spherical hyperopic treatment is associated with a higher risk for vision loss. Transition to a newer microkeratome model significantly reduced vision loss rate.

Interface Fluid Syndrome After Descemet Membrane Endothelial Keratoplasty in Patients With History of LASIK.

PURPOSE: The aim of this study was to evaluate the visual, pachymetric, tomographic, and biomicroscopic findings in a series of cases with laser in situ keratomileusis (LASIK) flap interface fluid syndrome (IFS) after Descemet membrane endothelial keratoplasty (DMEK). METHODS: Six cases were included in this study; all patients had a history of LASIK and underwent DMEK for the treatment of bullous keratopathy. After uneventful surgery, all patients presented with corneal edema and IFS under the LASIK flap, which was demonstrated with anterior segment optical coherence tomography (AS-OCT). Visual acuity, clinical findings, pachymetry, endothelial cell count, and AS-OCT were documented during the management of these cases. RESULTS: IFS appears 2.33 days (±1.03) after DMEK. One case improved with conservative treatment. In 5 cases, the LASIK flap was lifted, the fluid was drained, and the flap was replaced. The mean best-corrected visual acuity after fluid drainage was 0.44 logMAR (range 0.18-1.0) and mean central corneal thickness was 538 µm ± 160. Total resolution of the IFS was achieved at 14.5 days (range 4-30) after DMEK. AS-OCT showed resolution of the flap interface in 5 of 6 cases, while 1 patient required second DMEK due to reaccumulation of the interface fluid. CONCLUSIONS: IFS can occur after DMEK in patients with previous LASIK. AS-OCT is a valuable tool for monitoring these cases preoperatively and postoperatively. Early surgical management is often needed to achieve resolution.

Comparison of preoperative simulated and postoperative real safety distances using anterior segment OCT in patients with phakic IOL according to iris configuration.

AIM: To compare the simulated safe distance (SSD) preoperatively versus real safe distance (RSD) postoperatively in patients with iris-claw phakic intraocular lens (pIOL) implantation according to iris configuration. METHODS: Totally 60 eyes of 60 patients underwent pIOL implantation for surgical correction of myopia. Anterior chamber depth (ACD) was measured with the IOLMaster 700, and nasal and temporal safety distances (SD) were measured pre- and postoperatively using Anterior Segment Visante-OCT. SD was defined as a line measured between the edge of the optic or its simulated image to the endothelium. Eyes were divided into 3 groups: convex, concave, and plane according to preoperatory iris configuration. Statistical analysis was performed using the R program, for the comparison of independent groups and multiple comparisons, the Kruskal-Wallis test and the Dunn test were used respectively. RESULTS: Mean difference between nasal preoperative SSD and postoperative RSD was -0.36±0.38, -0.29±0.48, and -0.18±0.30 mm in the concave, convex, and plane group, respectively. Mean difference between temporal SSD and RSD was -0.36±0.37, -0.14±0.38, and -0.24±0.33 mm in the concave, convex, and plane group, respectively. There were statistically significant differences between SSD and RSS for both nasal and temporal sides in the concave and plane group (P<0.002). CONCLUSION: Preoperative SSD and postoperative RSD for iris-claw pIOL shows significant differences in patients with concave and plane iris.

Effect of Femtosecond Laser Cataract Surgery on Peripapillary Retinal Nerve Fiber Layer Thickness.

PRCIS: Femtosecond laser-assisted cataract surgery (FLACS) may cause thinning of the peripapillary retinal nerve fiber layer (pRNFL) in healthy eyes. PURPOSE: This prospective cohort study aimed to compare changes of pRNFL after FLACS using a liquid patient interface and conventional phacoemulsification cataract surgery (CPCS). PATIENTS AND METHODS: Included were 261 eyes (261 patients) with age-related cataracts and no ocular diseases scheduled either for FLACS (222 eyes) or CPCS (39 eyes). FLACS was performed using a Ziemer LDV Z8 laser. Average and quadrant pRNFL thickness was measured using optical coherence tomography before surgery and at 1, 3, and 6 months postoperatively. Postoperative changes in pRNFL thickness were compared within and between groups. RESULTS: Mean quadrant and average pRNFL thicknesses significantly increased after both surgeries (P<0.001). However, pRNFL thinning occurred after FLACS and CPCS (17% vs. 5.1%, respectively, P>0.05). FLACS eyes showed a significant and stable decrease of average pRNFL thickness (P=0.057) and a gradual decrease in pRNFL thickness of all quadrants (P≤0.018). CPCS eyes showed an initial increase of pRNFL thickness, followed by a decrease only in the nasal quadrant and average pRNFL. Preoperative pRNFL thickness was associated with thinning of the temporal quadrant (P=0.04). CONCLUSIONS: Both FLACS and CPCS demonstrated pRNFL thinning in some healthy eyes. Although the higher rate of pRNFL thinning after FLACS compared with CPCS lacked statistical significance, a consistent decrease in pRNFL thickness occurred in all quadrants and average pRNFL of FLACS eyes, suggesting that FLACS may lead to pRNFL thinning. Eyes with thinner preoperative pRNFL may be prone to temporal quadrant thinning after FLACS.

Corneal lenticule extraction assisted by a low-energy femtosecond laser.

A lenticule of intrastromal corneal tissue was cut together with 2 small incisions of 3.0 mm using a low-energy femtosecond laser system, FEMTO LDV Z8; 1 incision led to the posterior plane and 1 to the anterior, allowing dissection of the lenticule. When needed, recentering of the treatment area was possible without repeating the docking stage. Five eyes were operated, and a complete dissection and removal of the lenticule was achieved in all cases without any intraoperative complications. In addition, at postoperative day 1, all patients had a clear cornea. In conclusion, guided lenticule extraction using a low-energy femtosecond laser was a promising and easy procedure.